Hello everyone

I'm building a buggy car based on evo 7 engine (4g63t) and evo 6 transmission , transfer box and rear axle , without AYC/ACD or other 4x4 managment.
The Ecu model is MR560648 and it connected to the engine with the original harness.
I'm using 399 maf sensor , and the rom version is 98640014 ( Standard VII JDM Rom ID 98640014 ) .
The problem is that the engine doesn't run smoothly , it cant run in idle smoothly and can't run in high rpm , It's getting some missfire. Check engine light is turned on and with Evoscan (using OP 2.0) i'm getting TPS P0120 code.
Also i'm getting overcharge from the alternator 15.5V , but i'm not sure that's the main issue or cause.
I'm clueless and don't know if the problem starts from the TPS.
Any ideas ?

Thanks!